The tooth profile interlocking clearance between two mating gears of a gear transmission, the backlash, and in particular the rotational backlash, is known to create a hydrodynamic lubrication, compensating for dimensional changes caused by temperature effects, preventing abrasion or premature wear of the shaft, axles and toothed gears, and compensating bad construction and assembly work. In the serial production of engines, gears or other aggregates, providing a predetermined backlash to two or more toothed gears in mesh (serrated, helical, or other) pressed, screwed or secured otherwise onto driven or secondary shafts, requires elaborate alignment equipment or alignment devices.
WO2002/048575 describes a method of providing a predetermined backlash for a transmission comprising at least a first and a second interlocking toothed gear. The backlash according to this method is provided by positioning the first and the second gear with respect to each other by means of spacer material in the form of a removable coating applied to the upright sidewalls of the teeth of the first gear, the upright sidewalls being provided to face the teeth of the second gear. The first and second gears are positioned with respect to each other by adjusting their mutual position until they are positioned substantially play-free with respect to each other.
Afterwards the coating is mechanically, by rotational action of the gears during the test run of the engine in which they are incorporated, or chemically, by use of a solvent, removed from the first gear.
However, the method disclosed in WO2002/048575 is relatively difficult since application of the coating onto the upright sidewalls of the teeth of the gear is difficult. It is for example difficult, and therefore rather expensive, to adjust the thickness of the coating.
There is thus a need for a method to provide a predetermined backlash to a transmission comprising a first and a second interlocking toothed gear using spacer material which can be more easily applied to a tooth of the gear.